Physical vapor deposition (PVD) is commonly utilized for formation of thin films or layers. For instance, PVD is commonly utilized for deposition of thin layers in semiconductor structures, with PVD being particularly useful for deposition of metallic materials. PVD processes are commonly referred to as sputtering processes and can comprise sputtering of desired materials from a target. The sputtered materials are deposited across a substrate to form a desired thin film.
An exemplary PVD operation is described with reference to an apparatus 10 shown in FIG. 1. Apparatus 10 is an example of an ionized metal plasma (IMP) apparatus and comprises a chamber 12 having sidewalls 14. Chamber 12 is typically a high vacuum chamber. A target 16 is provided in an upper region of the chamber and a substrate 18 is provided in a lower region of the chamber. Substrate 18 is retained on a holder 20 which can typically comprise an electrostatic chuck. Target 16 can be retained within the chamber with suitable supporting members (not shown) which can include a power source. A shield 22 can be provided to shield chamber walls from sputtered material. Shield 22 is typically made of a conductive material.
Target 16 can comprise, for example, one or more of aluminum, cadmium, cobalt, copper, gold, indium, molybdenum, nickel, niobium, palladium, platinum, rhenium, ruthenium, silver, tin, tantalum, titanium, tungsten, vanadium, stainless steel and zinc. These target materials can be in elemental, compound or alloy form. The target can be a monolithic target or can be part of a target/backing plate assembly.
Substrate 18 can comprise, for example, a semiconductor wafer such as a single crystal silicon wafer.
During physical vapor deposition, material is sputtered from a surface of target 16 and directed toward substrate 18. The sputtered material is represented by arrows 24. Generally, the sputtered material will leave the target surface in a number of different directions. This can be problematic and it is preferred that the sputtered material be directed relatively orthogonal to an upper surface of the substrate 18. Accordingly, a focusing coil 26 is provided within chamber 12. The focusing coil can improve the orientation of sputtered materials as depicted in FIG. 1 by arrows 24a. As shown, initially sputtered material can be redirected by passing through coil 26 to proceed relatively orthogonal to the upper surface of substrate 18.
Coil 26 is retained within chamber 12 by support members 30. Supports 30 can typically provide attachment of coil 26 to shield 22. Because shield 22 and coil 26 are each conductive, support structure 30 can typically provide electrical insulation between the shield and the coil.
Coil 26 can typically be formed from a conductive material which is generally the same as the target since material can be sputtered from the coil by plasma ions during deposition processing.
Exemplary prior art mounting assemblies and coil mounting configurations are discussed with respect to FIGS. 2 and 3. Referring initially to FIG. 2, coil 26 can be mounted within a processing chamber by providing a support assembly 30 which passes through shield 22. In the prior art coil mounting assembly shown in FIG. 2, coil body 27 has an opening 25 which passes through the thickness of the coil body. A pin 36 can be inserted through the coil body for mounting purposes. A spacer or cup 38 can be mounted externally on coil body 27 and can surround inner pin portion 36. Support assembly 30 can comprise a multi-piece configuration having a first insulative piece 31 that passes partially or completely through shield 22. First insulator 31 can contact cup portion 38. A second insulative piece 32 can be provided externally to shield 22 relative to first insulator portion 31.
When the depicted coil is mounted within a processing chamber, the coil can be spaced from shield 22 by cup portion 38 and first insulator 30 disposed between coil body 27 and an interior or first site 21 of shield 22. Second insulator 32 can typically be disposed entirely on an external side 23 of shield 22 and can interface the shield opposing first insulator 31.
Assembly 30 can further comprise a fastener 34 such as a bolt or screw as shown in FIG. 2. The fastener can extend through insulative support parts 32, 31 and can insert into centrally disposed pin portion 36 for mounting coil 26 within shield 22.
Coil 26 as shown in FIG. 2 is generally provided within the chamber as a kit comprising pins 36, retaining screws 34, cups 38, and insulative pieces 31 and 32 along with various other components (e.g. inner conductor components) which are not shown in FIG. 2. The coils utilized in such kits will comprise annular rings (referred to herein as annular bodies or annular coil bodies) having openings extending therethrough. Coil 26 will wear out with time and replacement kits are provided for replacement of the coil. Such kits will typically comprise a coil together with the numerous separate components for attaching the coil to the shield. The kit is assembled in order to provide the coil within the chamber and assembly typically comprises assembling the various components and inserting fastener 34 which is typically threadably engaged within an interior periphery of pin 36.
The coil structure shown in FIG. 2 is an exemplary pin and cup type prior art coil structure. Other pin and cup type structures and mounting configurations have been developed. For instance, monolithic coil structures have been constructed in which cups and inner conductors and/or the pin portion are one-piece with the coil. An advantage of forming monolithic coils structures is that such can eliminate utilization of pins and thereby eliminate discontinuities along an inner peripheral surface of a coil by eliminating the recessed pinhead otherwise present along the inner periphery of the coil. An advantageous of eliminating discontinuities from the inner periphery of the coil is that such can improve longevity of the coil and performance of the coil.
An exemplary prior art mounting assembly for utilization with a monolithic coil is depicted in FIG. 3. As shown, coil 26 has a protrusion or ‘boss’ 40 which is integral with coil body 27. Boss structure 40 can be configured to mimic a combination of pin and cup features such as those shown in FIG. 2. The boss configuration 40 shown in FIG. 3 is but an exemplary configuration and alternative boss shapes and structures have been developed. Mounting of a monolithic coil can typically utilize prior art support assemblies having a first insulative component 31 which extends through shield 22 as shown in FIG. 3. Insulator 31 can insulate a fastener 34 thereby electrically isolating the fastener from shield 22. The assembly can further comprise a second insulator disposed externally to shield 22 relative to internally disposed coil 26 and first insulator 31. Mounting of monolithic coil 26 can comprise insertion of fastener 34 through insulator portions 32 and 31 and threadably engaging fastener 34 into a threaded portion of boss 40.
Monolithic coil structures which have been produced have been utilized in modified physical vapor deposition apparatuses. In other words, the monolithic coil assemblies have not corresponded to assemblies which can be substituted for kit constructions utilized in conventional physical vapor deposition apparatuses, but instead have differences which make them suitable for apparatuses other than conventional apparatuses described above. Regardless of whether the coil kits comprise a monolithic coil and assembly as shown in FIG. 3 or the prior art pin and cup coil with the support assembly shown in FIG. 2, such prior art coil kits can be difficult to mount within a processing chamber. Pin and cup coil configurations and corresponding assemblies such as that shown in FIG. 2 can be difficult to mount due to the need to align and correctly assemble multiple pieces during the mounting process. Although the monolithic target shown in FIG. 3 reduces the number of pieces which must be simultaneously aligned during mounting, the limited space within the confines of shield 22 can make positioning and alignment of the coil within the shield extremely difficult. Typical prior art configurations of insulator parts 31 and 32 such as those depicted in FIGS. 2 and 3 can add to the difficulty in coil mounting.
It would be desirable to develop new configurations for coil support assemblies.